Field of the Invention
The invention relates to a flame sensor and, more particularly, to a fiber optic flame sensor for sensing specific characteristics of a flame in a combustion chamber.
Discussion of Prior Art
Within an oil or gas fueled turbine, fuel is fed into a combustion chamber within which an ignition flame is present. If the flame becomes extinguished, commonly referred to as a flame-out condition, it is a concern that fuel may continue to be fed into the hot combustion chamber without appropriate ignition. Damage to the turbine can occur if the fuel is inappropriately ignited (e.g., ignition caused by something other than the ignition flame in view of the absence of the flame). Consequently, if the ignition flame is extinguished within the combustion chamber, it is critical that the fuel feed into the combustion chamber is quickly terminated and thus limit un-combusted fuel build up.
A flame sensor is generally used for detecting the presence or absence of an ignition flame within a combustion chamber of a gas turbine. Also, flame sensing electronics are commonly associated with the flame sensor within the turbine arrangement. The flame sensing electronics may be temperature sensitive. Due to the relatively hot temperatures in and near the combustion chamber, water cooling is often used to cool the temperature sensitive flame sensing electronics. However, water may occasionally leak and, if sprayed on the relatively hot housing of the turbine, may cause the turbine housing to contract, causing damage to the turbine. Accordingly, it would be useful to provide a flame sensor that eliminates the need for water cooling and which circuitry is not affected by the relatively high temperature near the combustion process/chamber.